Ok, read in a Google search that "Items that are not present in the default menu will only be included in the generated menu if their "Custom" flag is set." Cool. WHERE do we set the "Custom" flag? I want an item to show on the Ozh horizontal menu.

That's outdated information. The current version doesn't have an editable "custom" flag any more and user-created items are always included. To create a menu item, click the "New menu" toolbar button (it's the 4th button from the left).